Conventionally, an interface method of directly reacting bisphenols and carbonyl chloride, and a melt method of polycondensation reacting bisphenols and a carbonic diester by an ester exchange reaction are known as a production method of an aromatic polycarbonate resin. Above all, the melt method by an ester exchange reaction has the advantage that an aromatic polycarbonate resin can inexpensively be produced as compared with the interface method.
The melt method conducts a polycondensation reaction at high temperature under high vacuum, and therefore, a polycarbonate resin formed is liable to color. For this reason, a production method of using a stainless steel-made reactor washed with a liquid containing an aromatic hydroxy compound is reported as a method of preventing such a coloration of a resin (see Patent Document 1).
Furthermore, a method wherein after stopping a melt polymerization reaction, a molten reactant is withdrawn, a resin remained in a reaction tank or the like is dissolved and washed with a washing liquid containing a monohydroxy compound, a carbonic diester and the like within 24 hours, and the inside of an apparatus is held under an inert gas atmosphere is reported (see Patent Document 2).
[Patent Document 1] JP-A-6-056984
[Patent Document 2] JP-A-2004-197004